Arrangement for centering, aligning and retaining a rotating record

Abstract

An arrangement for centering, aligning and retaining a rigid disc such as a rapidly rotating video disc in an operating position, comprising a centering device mounted on a drive spindle, which device cooperates with a central disc hole in the disc, comprising a disc aligner mounted on the drive spindle for aligning the disc in a plane perpendicular to the axis of rotation of the drive spindle in the operating position of said disc, and comprising a disc loader for loading the disc towards the disc aligner. The disc aligner is rigidly connected to the drive spindle and the centering device comprises a plurality of resilient centering members which cooperate with the wall of the disc hole and which are radially movable between a rest position and an operating position which is situated nearer the axis of rotation of the drive spindle.

What is claimed is: 
     
       1. An improved arrangement for centering, aligning and retaining a rotary disc-shaped rigid record with a central disc hole in an operating position, the arrangement comprising: a drive spindle with a free end, which spindle is rotatable about an axis of rotation,   a centering device disposed on the drive spindle near its free end, which device cooperates with a wall of the central disc hole in the operating position of the disc,   a disc aligner which is mounted on the drive spindle for aligning the disc in its operating position in a plane perpendicular to the axis of rotation of the drive spindle and provided with one or more supporting surfaces for the disc, as well as   a disc loader which is movable to a position opposite the centering device and which presses on a disc in the operating position, for retaining the disc in position in conjunction with the supporting surfaces of the disc aligner, the improvement being characterized in that   the disc aligner is rigidly connected to the drive spindle,   the centering device comprises a plurality of centering members which are radially movable between a rest position and an operating position which is situated nearer the axis of rotation, and   there are provided resilient means for urging the centering members towards their rest positions, the centering members being movable against the action of the resilient means solely by cooperation with the wall of the disc hole when the disc is placed onto the drive spindle and axially moved toward its operating position.   
     
     
       2. An arrangement as claimed in claim 1, characterized in that the resilient means for the centering members comprise bar springs which are integral with the centering members, which springs are connected to the drive spindle by a fixed end. 
     
     
       3. An arrangement as claimed in claim 2, characterized in that the bar springs, at least on a side which is remote from the axis of rotation of the drive spindle, have a kinked shape, so that on a side which is disposed nearer the free end of the drive spindle the bar springs together constitute an interrupted truncated cone in the rest position, which cone has a transverse dimension which varies from smaller than to greater than the diameter of the disc hole, and furthermore on a side which is more remote from the free end of the drive spindle together constitute an interrupted cylinder in the operating position, which cylinder has a transverse dimension equal to the diameter of the disc hole. 
     
     
       4. An arrangement as claimed in claim 1, characterized in that the resilient means for the centering members have a spring constant, (which is defined as the quotient of the change in resilient force and the change in resilient depression, which upon a displacement of the centering means from the rest position into the operating position changes from smaller to greater. 
     
     
       5. An arrangement as claimed in claim 2, characterized in that each bar spring has a free end and that there are provided stop means on the drive spindle with which, in a position situated between the rest position and the operating position, each of the bar springs cooperates near its free end, so as to obtain a stepwise change of the spring constant. 
     
     
       6. An arrangement as claimed in claim 2, characterized in that the centering device is mounted on the drive spindle as one unit, comprising the bar springs as well as a retaining ring which interconnects said springs and which is integral therewith. 
     
     
       7. An arrangement as claimed in claim 6, characterized in that the centering device is integrally manufactured from plastic. 
     
     
       8. An arrangement as claimed in claim 5, characterized in that the stop means comprise wall portions of a coaxial cylindrical stop member which is rigidly mounted on the drive spindle.